Generally, a navigation system is a system which provides information for driving of a transportation device, such as a vehicle, using an artificial satellite. The navigation system is also referred to as an automatic navigation system.
A typical navigation system is configured into one terminal and includes a storage medium to store map data. Also, the navigation system includes a Global Positioning System (GPS) receiver to receive GPS signals.
The navigation system calculates a location of a vehicle, and informs a user of a current location of the vehicle based on the calculated location of the vehicle. Also, the navigation system routes an optimal path from the current location to the user's desired destination and guides the user to the desired location, providing the user with various types of associated information along the path.
A method of calculating a location of a vehicle receives location data from a GPS satellite using a GPS receiver, and calculates the current location of the vehicle based on the received location data.
Another method of calculating a location of a vehicle calculates the current location of the vehicle using a gyro sensor and an acceleration sensor, which are installed in the vehicle. In this instance, the other method receives GPS signals, calculates the current location of the vehicle based on the received GPS signals, and corrects the calculated current location based on results detected by the gyro sensor and the acceleration sensor.
Also, a slope value of a sensor is determined using the acceleration sensor and an inclination of a vehicle is determined based on the determined slope value. For this, the acceleration sensor is vertically mounted in a front/side/bottom surface of a vehicle. The condition that an output value of the acceleration sensor is set as an initial value is required when a vehicle is in a horizontal state.
Specifically, in order to determine whether the vehicle is currently inclined using a three-axis acceleration sensor installed in the vehicle, or embedded in a PND-typed terminal installed in the vehicle, the inclination of the vehicle may be determined using a value of a Y axis near to a travel direction of the vehicle and a value of a Z axis vertical to the ground.
In this instance, when a front portion of the vehicle goes up, that is, when the vehicle is in the inclining-slope driving state, gravity acting on the Y axis may increase to thereby increase a measurement value. Conversely, when the front portion of the vehicle goes down, that is, when the vehicle is in the declining-slope driving state, the measurement value of the Y axis may be decreased. In both cases where the front portion of the vehicle goes up and where the front portion of the vehicle goes down, the Z axis may be decreased.
In the conventional art, when the vehicle is being driven, the value of the Y axis may be measured by adding the force by the gravity and the force by acceleration/deceleration. Therefore, an inclination level cannot be measured using only the measurement value.
If it is possible to separate a measurement value by the gravity and a measurement value by the acceleration/deceleration, the inclination level may be measured using only the measurement value by the gravity. However, it is impossible to separate the above two forces from each other.
Accordingly, proposed is a method that can more accurately determine a driving state of a vehicle using an acceleration sensor value and a current speed.